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Y2 - Endocrine > Physiology > Flashcards

Physiology Flashcards

(74 cards)

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1
Q

What is autocrine regulation?

A

Chemicals released from the cells bind to receptors on or in the cell that is releasing them

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2
Q

What is paracrine regulation?

A

Chemicals released from the cells bind to receptors on adjacent cells

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3
Q

What is endocrine regulation?

A

Chemicals released from secretory cells are usually transported via the circulatory system

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4
Q

What are hormones?

A

Any substance produced by one cell to regulate another cell

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5
Q

How does the hypothalamus control endocrine regulation?

A

Secreted regulator hormones that control the activity of anterior pituitary cells
Synthesises hormones and transports them to the posterior pituitary via the infundibulum
Direct neural control function - controls secretion of adrenaline and noradrenaline by the adrenal medulla

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6
Q

What is diurnal control?

A

Where external cues (light/dark) evoke fluctuations in hormone secretions

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7
Q

What is an examples of hormones having complementary actions?

A

Adrenaline, cortisol and glucagon have complementary actions on blood glucose levels

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8
Q

What is an examples of hormones having antagonistic actions?

A

Insulin and glucagon have antagonistic effects on blood glucose levels

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9
Q

What are the 3 classes of hormones?

A

Steroids
Amine derived
Proteins

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10
Q

What are steroid hormones?

A

Lipids derived from cholesterol

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11
Q

How are steroid hormones transported?

A

In blood plasma by binding to carrier proteins

Some (10%) are free and biologically active

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12
Q

What are examples of steroid hormones?

A

Cortisol
Oestrogen
Testosterone

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13
Q

How do steroid hormones pass through plasma membranes?

A

Activated hormone-receptor complex forms within the cell

The complex binds to DNA and activates specific genes - gene activation leads to production of key proteins

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14
Q

What are amine derived hormones?

A

Hydrophilic hormones derived from amino acids

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15
Q

How are amine derived hormones transported?

A

Unbound in blood plasma

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16
Q

Where are amine derived hormones secreted from?

A

Thyroid and adrenal medulla

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17
Q

What are examples of amine derived hormones?

A

Thyroxine
Adrenaline

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18
Q

What are peptide hormones?

A

Hydrophilic hormones that make up the majority of hormones

The same thing as protein hormones

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19
Q

Where are peptide hormones secreted from?

A

Pituitary gland, parathyroid gland, heart, stomach, liver, kidneys

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20
Q

In what form are peptide hormones secreted as?

A

Precursor molecules and stored in secretory vesicles

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21
Q

What are examples of peptide hormones?

A

Somatostatin

Insulin

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22
Q

What is the process of insulin secretion?

A
  1. Elevation of blood glucose concentration
  2. Increased diffusion of glucose into the b-cell (aka B-cell) by facilitated transport (GLUT2)
  3. Phosphorylation of glucose by glucokinase
  4. Glycolysis of glucose-6-phosphate in mitochondria yielding ATP
  5. Increased ATP/ADP ratio within cell closes ATP-sensitive K+ channels causing membrane depolarisation
  6. Opening of voltage-activated Ca2+ channels increases intracellular Ca2+ that triggers insulin secretion
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23
Q

What is the purpose of the binding of hormones to career proteins?

A

Facilitation of hormone transport
Increased half-life
A reservoir for the hormone

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24
Q

What are examples of specific carrier proteins?

A

Cortisol-binding globulin binds cortisol selectively
Thyroxine-binding globulin binds thyroxine (T4) selectively
Sex steroid-binding globulin binds mainly testosterone and oestradiol

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25
What are the hormones secreted by the hypothalamus?
Thyrotropin releasing hormone (TRH) | Corticotropin releasing hormone (CRH)
26
What are the hormones released by the pituitary gland?
``` Thyroid stimulating hormone (TSH) Adrenocorticotrophic Hormone (ACTH) Luteinizing Hormone (LH) Follicle Stimulating Hormone (FSH) Growth Hormone (GH) Prolactin Melanocyte Stimulating Hormone (MSH) Oxytocin Antidiuretic Hormone (ADH) ```
27
What are the hormones released by the pineal gland?
Melatonin
28
What are the hormones released by the thyroid/parathyroid glands?
Thyroxine (T4) Triiodothyronine (T3) Calcitonin (CT) Parathyroid Hormone (PTH)
29
What are the hormones released by the adrenal medulla?
Adrenaline (epinephrine) | Noradrenaline (norepinephrine)
30
What are the hormones released by the adrenal cortex?
Dehydroepiandrosterone (DHEA) Aldosterone Glucocorticoids (cortisol, corticosterone
31
What are the hormones released by the testes?
Testosterone
32
What are the hormones released by the pancreas?
Insulin Glucagon Somatostatin
33
What are the hormones released by the ovaries?
Oestradiol Oestriol Progesterone Testosterone
34
What are the hormones released by the placenta?
Human Chorionic Gonadotrophin (hCG) | Oestradiol
35
What are the hormones released by the mammary glands?
Oestrogen
36
What is the cause of Diabetes mellitus (Type I)?
Lack of insulin
37
What is the cause of Diabetes mellitus (Type II)?
Insulin resistance, overproduction of glucose or abnormal insulin secretion
38
What is the cause of Diabetes insipidus (pituitary)?
Lack of ADH
39
What is the cause of Diabetes insipidus (nephrogenic)?
Renal unresponsiveness to ADH
40
What is the cause of Addison’s disease?
Adrenal destruction/lack of ACTH secretion
41
What is the cause of Cushing's syndrome?
Adrenal tumour (excess cortisol secretion)
42
What is the cause of Congenital hypothyroidism?
Lack of T4-T3 secretion
43
What is the cause of Myxedema (adult hypothyroidism)?
Lack of T4-T3 secretion
44
What is the cause of Hyperthyroidism?
Excess of T4-T3 secretion
45
What is the cause of Hypoparathyroidism?
Parathyroid gland destruction
46
What is the cause of hyperparathyroidism?
Parathyroid gland tumour, increased PTH secretion
47
What is the cause of Conn’s disease (hyperalosteronism)?
Adrenocortical tumour, excess aldosterone secretion
48
Which hormone acts on the adrenal gland, which hormone triggers its release, and which hormone does it stimulate the production of?
ACTH CRH Cortisol
49
Which hormone acts on the thyroid gland, which hormone triggers its release, and which hormone does it stimulate the production of?
TSH TRH T3/4
50
Which hormones act on the ovaries and testes, which hormone triggers their release, and which hormones do they stimulate the production of?
LH, FSH GnRH Oestradiol, Testosterone
51
Which hormone is responsible for growth and which hormone triggers its release?
GH IGF-1
52
Which hormone acts on the mammary glands and which hormone triggers its release?
Prolactin | Dopamine INHIBITS release of prolactin
53
What hormones are measured in a normal pituitary blood test?
``` TSH fT4 LH FSH Testosterone GH IGF-1 PRL ```
54
What are the key reproductive hormones?
``` GnRH LH FSH Oestrogen Progesterone Testosterone ```
55
What are the gonadotrophin hormones?
LH, FSH
56
What are the functions of FSH in males and females?
Males: stimulates testes to produce sperm (spermatogenesis) Females: causes growth of ovarian follicles (oogenesis) and stimulates the ovary to secrete oestrogen
57
What are the functions of LH in males and females?
Males: causes the testes to secrete testosterone Females: causes ovulation and causes progesterone production by the corpus luteum
58
What is the female HPG (hypothalamic-pituitary-gonadal) axis?
Hypothalamus released GnRH, which stimulates the pituitary to release LH and FSH. LH and FSH stimulate the ovaries to secrete oestrogen and progesterone. High levels of oestrogen and progesterone both inhibit and stimulate the pituitary and hypothalamus at different parts in the cycle
59
What is the male HPG (hypothalamic-pituitary-gonadal) axis?
Hypothalamus released GnRH, which stimulates the pituitary to release LH and FSH. LH and FSH stimulate the testes to produce testosterone. High levels of testosterone inhibit the hypothalamus and pituitary
60
What is GnRH?
Gonadotrophin Releasing Hormone is a neuropeptide synthesised and released by the hypothalamus
61
In what way is GnRH release different in males and females?
In males: secretes in pulses at a constant frequency | In females: secreted in pulses which vary in frequency during the menstrual cycle
62
How is frequency of GnRH pulses regulated?
Growth of follicles increases oestrogen concentration, which will increase GnRH pulsatality, driving release of LH The corpus luteum causes increase in progesterone concentration, which reduces frequency of GnRH pulses
63
How do the levels of different hormones change throughout the menstrual cycle?
At the start FSH rises, causing growth of ovarian follicles which secrete oestrogen, increasing levels Rising oestrogen levels cause negative feedback loop to lower FSH temporarily Once oestrogen reaches a certain level it causes a positive feedback mechanism to increase FSH levels and cause a surge in LH LH surge causes ovulation and the formation of corpus luteum, which secretes progesterone Increased levels of progesterone decrease LH secretion If fertilisation doesn't occur progesterone levels drop again
64
What is a follicle?
Oocyte surrounded by follicular cells
65
What is the function of the negative then positive feedback of FSH levels?q
To select one follicle to be secreted
66
What happens to the corpus luteum is pregnancy does not occur?
Becomes the corpus albicans
67
What are the functions of oestrogen?
Increase the thickness of the vaginal wall Regulate the LH surge Reduce vaginal pH through increased lactic acid production Decrease viscosity of cervical mucus to facilitate sperm penetration
68
What are the functions of progesterone?
Maintains thickness of the endometrium Responsible for infertile thick mucus to prevent sperm transport and help prevent infection Relaxes the myometrium (smooth muscle)
69
What factors regulate sperm's ability to penetrate the mucus?
Thickness of the mucus Motility of sperm Interaction with reactive oxygen species produced by leukocytes int he cervical mucus Interaction with mucins
70
Where does spermatogenesis occur?
Seminiferous tubules in the testes
71
Roughly how long does spermatogenesis take?
70 days
72
What is the function of testosterone in spermatogenesis?
Stimulates release of spermatocytes from sertoli cells | Maintains the integrity of the blood-testis barrier
73
How is testosterone produced?
LH stimulates testosterone production from cholesterol in Leydig cells
74
How are testosterone and LH linked?
Negative feedback - rise in testosterone decreases LH and decrease in testosterone increases LH

Y2 - Endocrine (9 decks)

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